There are many environmental concerns associated with the emission of pollutants from gas turbine engines. This has led to stricter emissions standards to regulate and reduce the exhaust gas levels of pollutants from gas turbine engines. These standards regulate the emission of oxides of nitrogen (NOx), unburned hydrocarbons and smoke, and carbon monoxide (CO) from the engines of aircrafts.
Effectively, to control the emission of pollutants, the fuel and air must be well mixed so that burning occurs evenly across the mixture.
Mixing of fuel and air is achieved by the use of swirlers with the combustor. The swirler comprises a plurality of vanes arranged in a circular geometry. The vanes define flow slots between adjacent vanes. The flow slots provide passage for flow of fuel and air. Fuel is supplied by means of fuel injectors usually located on the flow paths. The swirler mixes swirlly the incoming air and the injected fuel.